The present invention relates to carotenoid compounds, and more particularly to carotenoid-oil dispersions encapsulated within protective starch encasements.
Carotenoids are a class of organic pigments that are often used to provide safe coloration of food. Carotenoids include carotenes (e.g., beta-carotene and lycopene), which are C.sub.40 carotenoids containing 11 or fewer conjugated carbon-carbon double bonds, and xanthophylls (e.g., lutein and astaxanthin), which are oxygen-containing carotenoids. Carotenoids are moderately soluble in oil and are insoluble in water.
In addition to the use of carotenoids as pigments, some carotenoids also have nutritional value. For example, beta-carotene is widely used as a vitamin A precursor (i.e., provitamin A) since beta-carotene is metabolically oxidized to vitamin A (retinol) in most animals.
One problem associated with carotenoids is their susceptibility to oxidation. For example, beta-carotene will react with oxygen from the air, resulting in an inactive, colorless oxidation product. Thus, over time, a carotenoid that is exposed to air without the protection of encapsulation and/or antioxidants will lose its pigmentation and nutritional attributes.
Carotenoids are often supplied in oil dispersions rather than in crystalline form in order to "stabilize" the carotenoids, that is, reduce the amount of the degradation caused by exposure to oxygen, heat, or light. Further, carotenoids supplied in an oil dispersion are less susceptible to damage from handling during transportation. Additionally, it is believed that carotenoids in an oil dispersion are more readily absorbed or ingested, and thus have better nutritional attributes.
It is known that liquid and solid chemical agents that are "sensitive" (i.e., subject to degradation when exposed to external elements) can be protected by encapsulating them within a dry starch matrix. For example, U.S. Pat. No. 2,876,160 to Schoch et al teaches the protection of agents (e.g., insecticides, flavoring oils, fatty acids, medicinals, and beta-carotene) from physical and chemical deterioration by encapsulating the agent within a starch matrix. In that method, a liquid or solid agent is gradually added with vigorous agitation, which may include agitation by use of a mechanical emulsifier or pressure homogenizer, to an aqueous starch solution, which may contain plasticizers such as glucose syrup. The resulting emulsion or dispersion is dried using methods such as spray-drying. If a solid agent is to be protected, it may be "powdered" prior to adding it to the starch solution.
Other examples of starch encapsulation of sensitive agents are disclosed in U.S. Pat. No. 4,276,312 to Merritt (teaching the protection of vitamins and flavor agents from oxidation or sunlight deterioration by spray-drying a mixture of the agent and starch mixture to form rod-like particles) and U.S. Pat. No. 2,827,452 to Schlenk et al (teaching the use of a starch matrix to protect an agent such as vitamin A acetate from oxidation).
Several variations of the dry starch-coating method have been used to protect sensitive agents, such as flavorings, oils, and vitamins, from sunlight and oxygen. For example, a starch/agent mixture can be partially dried and then ground into a powder (U.S. Pat. Nos. 4,230,687 to Sair et al and 4,911,952 to Doane et al), or the starch/agent mixture can be quenched in oil and then dehydrated to form beadlets (U.S. Pat. No. 3,666,557 to Jensen et al).
While it is important to encapsulate a carotenoid dispersion with a sufficient amount of coating to protect the carotenoids from degradation, it is advantageous to minimize the amount of coating relative to the amount of carotenoid in order to minimize the amount of inactive ingredients that merely add to the bulk of a product containing the encapsulated carotenoid-oil dispersion. For example, if a dry-powder carotenoid dispersion is to be used in a tablet, a bulky coating of unnecessary ingredients can interfere with the tableting process. If the dry-powder carotenoid is to be used in a powdered drink mix, a bulky coating of unnecessary ingredients can needlessly increase the volume and weight of the drink mix. Thus, it is preferable to maximize the "potency" (i.e., the concentration of carotenoid) of the encapsulated carotenoid-oil dispersion in order to limit the amount of inactive ingredients.
The art discloses methods of increasing the stability of dry-powder carotenoid products. However, the potency of the carotenoid products is relatively low; and stability is achieved by utilizing synthetic (i.e., not produced by nature) ingredients.